Add configuration section

Author: gallib

README.md

@@ -18,3 +18,10 @@ php artisan migrate
 ```
 
 And that's all. Laravel short url is now set up on your homepage.
+
+## Configuration
+
+Laravel Short Url configuration file could be found on ``` config/shorturl.php ```
+
+route_form_prefix : Prefix the form to shorten an url
+route_redirect_prefix : Prefix the code of the short url